In our U.S. Pat. No. 4,002,012 issued Jan. 11, 1977, there is shown a splicing apparatus which operates to join the ends of yarns using a circumferential air jet to spin the yarns. By this spinning procedure, the fibers of the yarns are moved rapidly and the heat generated by fiber friction operates, with thermoplastic yarns, to bond adjacent fibers.
It has been found that the splicer shown in that patent operates to join either staple or continuous filament yarns. However, it has also been found that it is too slow in operation to be used as part of a high speed continuous self-twist yarn making system because its operation is based on work heating of the fibers. Consider, for example, a system in which false-twist, self-twist yarns are to be produced at a rate of 100 yards per minute with two twist reversals per yard and wherein the nodes (the locations of twist reversal) of adjacent strands are to be joined to each other before self-twisting. It will be apparent that the fixation or joining device will need to operate 200 times per minute. In practice, somewhat less than 1/200 of a minute (5 milliseconds) is available for each joining, and it is therefore necessary to have a joining device which will accomplish its task in order that the joining step itself not be a factor limiting the speed of the entire production system.
It will also be recognized that joining devices as employed in previous systems rely upon pushing filaments from one yarn strand into between and among filaments of a second strand, and that this is only possible if the two bundles of filaments which comprise the strands are loosely packed and can easily be separated from each other. This condition is not present if either one of the strands contains any twist since the twist constricts each bundle of filaments into a relatively coherent strand. It will also be noted that a similar tightly constricted condition exists if the tension in the strands is too high.